Calculating Simple Probability
Calculate the probability of a simple event with equally likely outcomes using the formula: probability = number of favourable outcomes ÷ total number of possible outcomes; express the result as a fraction in its simplest form; apply to rolling dice, drawing from bags, and other simple chance situations
Lesson
Set out your lesson
“Calculating Simple Probability means practising the idea at the table with counters or paper models and one clear check. We will demo once, then your child tries.”
Bring to the table
- Paper strips or a folded circle
- Pencil and labels (1/2, 1/4)
Extra for the adult
Worked example. Fold a strip in half: each piece is 1/2 of the whole.
Optional challenge. For Calculating Simple Probability, add one harder example after success.
What to notice. Keep one parent note: examples tried; results; support used. This session samples Calculating Simple Probability, not mastery.
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1 approach
Calculating Simple Probability means practising the idea at the table with counters or paper models and one clear check. We will demo once, then your child tries.
Materials: Paper strips or a folded circle; Pencil and labels (1/2, 1/4). Adult folds a strip into halves and labels 1/2. Child makes three fair shares (halves/quarters) and names each piece. Done: three correctly named equal parts. Stop after the fresh check; keep optional challenge for another day.
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Start practiceCalculating Simple Probability practice
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Learning resources
Extra practice links — they do not replace Gakuva’s teaching approach.
PhET Interactive Simulations · Practice link — not the full lesson
Plinko Probability
Before you open · source notes
Plinko Probability supports hands-on exploration for Calculating Simple Probability. Not every lab worksheet.
Free interactive page, no sign-in required for the tested path.
Before you openAsk the learner what they changed in the sim or page and what they observed.
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Source, access and review notes
Public PhET Interactive Simulations page. An anonymous GET on 2026-11-12 returned HTTP 200 with no login or payment prompt for this URL. Opening the link does not save practice or assess mastery. An adult should preview and guide the learner.
PhET Interactive Simulations. “Plinko Probability.” External page; Gakuva does not copy, host, embed, or redistribute materials.
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Check understanding
- Calculate the probability of drawing a blue marble from a bag of 3 blue and 7 red as 3/10
- Use the formula P(event) = favourable outcomes ÷ total outcomes to solve at least three different problems
- Explain why increasing the number of favourable outcomes increases the probability
“If there are 3 red and 7 blue balls in a bag, can your child work out the probability of picking a red one and express it as a fraction in its simplest form?”
Curriculum record
- Type
- Procedural
- Subject
- Mathematics
- Domain
- Probability
- Age range
- Ages 10–13
Standards